Process and apparatus for making glass fiber structures including coating before and after attenuation

ABSTRACT

In making glass fiber structures, the strands of glass are first coated with a liquid, for instance a lubricant, prior to their delivery to the drawing drum, and the glass fibers formed on the drawing drum are then coated in a separate application, while separated from each other, with a liquid coating medium after their removal from the drawing drum and prior to their consolidation into a glass fiber structure. An apparatus for carrying out the second coating application includes an air channel leading away from the drawing drum and liquid transfer means protruding into the air channel so as to be contacted by the glass fibers carried through said air channel in a stream of air.

July 11, 1972 w. SCHULLER ET AL 3,676,096

PROCESS AND APPARATUS FOR MAKING GLASS FIBER STRUCTURES INCLUDINGCOATING BEFORE AND AFTER ATTENUATION Filed July 16, 1969 2 Sheets-Sheet1 0 INVENTOR$ 2446 4 By 7 w i M1914 md-d i/a /Z/% July 11, 1972 w.SCHULLER ETAL 3,676,096

PROCESS AND APPARATUS FOR MAKING GLASS FIBER STRUCTURES INCLUDINGCOATING BEFORE AND AFTER ATTENUATION Filed July 16, 1969 2 Sheets-Sheet2 United States Patent O PROCESS AND APPARATUS FOR MAKING GLASS FIBERSTRUCTURES INCLUDING COATING BEFORE AND AFTER ATTENUATION WolfgangSchuller, Wertheim am Main, and Harald Hohlfeld, Wertheim (Nord),Germany, assignors to Werner Hugo Wilhelm Schuller, Munich, Grunwald,Germany Filed July 16, 1969, Ser. No. 842,271 Claims priority,application Germany, July 18, 1968, P 17 71 833.1 Int. Cl. C03c 25/02US. Cl. 65-3 16 Claims ABSTRACT OF THE DISCLOSURE In making glass fiberstructures, the strands of glass are first coated with a liquid, forinstance a lubricant, prior to their delivery to the drawing drum, andthe glass fibers formed on the drawing drum are then coated in aseparate application, while separated from each other, with a liquidcoating medium after their removal from the drawing drum and prior totheir consolidation into a glass fiber structure.

An apparatus for carrying out the second coating application includes anair channel leading away from the drawing drum and liquid transfer meansprotruding into the air channel so as to be contacted by the glassfibers carried through said air channel in a stream of air.

BACKGROUND OF THE INVENTION Glass fiber structures are usually made byfirst forming filaments of glass in a continuous process from streams ofliquid or softened glass by means of a drawing drum rotating at highspeed. Before a complete revolution of the drum is eifected with thefilaments of glass laying side by side on it, they are lifted from thedrum by a scraper or stripper and at that time split up into staplefibers of uneven length. The thus-formed fibers are then suspended in astream of air, are conducted along guide walls and finally, afterelimination of the air, consolidated to the fibrous structure desired asend product at a place remote from the drawing drum. The final productmay for instance be a plane fibrous structure such as a mat or fleece orit may be a ribbon-shaped structure such as a sliver or a yarn, or itmay also be a three-dimensional body such as tube sections (see GermanPats. 824,456 and 976,782).

Both the filaments and the subsequent fibers must be coated with aliquid medium in order to effect the taking with or driving of thefilaments by the drum and in order also to form the final body from thefibers. The filaments are usually coated on the way from the spinningplace to the place where they first touch the drawing drum. Theconventional device for this purpose is a pad which extends across thewidth of the moving filaments or across the width of the drawing drumand consists of an absorptive material.

This pad is placed in a manner that the sidewise aligned filaments willcontact it if possible under tension. The pad is soaked with the liquidto be coated. The pad can also consist of a cloth supported on a rod andmay be supplied with fresh liquid by a dropping device in accordancewith the amount of use. For the practical execution of these devices itis not easy to transfer the liquid from the pad to the filaments whichare drawn off at a high speed, that is above 2,900 m./min. There havebeen many proposals for devices of this kind. The one most successful isthat published in Austrian Pat. 218,191.

The coating of the filaments taken by the drum with a liquid which inindustrial practice is called oiling has a triple function. One purposeis to impart to the filaments an adhesion to the surface of the drawingdrum during the high speed revolution, which adhesion must be sufficientto prevent slippage between the single filament and the drum surface.The coating should in addition make the individual glass filamentssupple and flexible to prevent abrasion or other mechanical damageduring the further processing. The glass fibers or staple fibers whichare formed from the glass filaments in the subsequent processing and areconsolidated to the glass fiber structure, for instance a sliver or afleece, must in addition obtain a certain tensile strength which issecured by the cohesion or adhesion between the fibers.

Apart from these various purposes of the coating, liquid coatingmaterial may also be used for other reasons, for instance in order todye the glass fiber structures.

The coating medium, mostly of the emulsion type consists of differentorganic or inorganic oils and additives which stabilize the emulsion,increase the flexibility of the filaments drawn, and have an adhesive,hardening and antistatic effect. Whereas flexibility is a feature whichmainly concerns the drawing of the filaments by the drum and theirtaking-off therefrom, the adhesive nature of the coating medium is aproperty, which brings disadvantages for the drawing drum and thestripper insofar as their surfaces get sticky and dirty therefrom.

In practical use, it is diflicult to perform all these three functions,the difliculties arising both as to the composition and as to the dosageof the coating material such as lubricant. Usually it was thereforenecessary to make a compromise between the various requirements, that isto form a multicomponent liquid which would accomplish the variouspurposes. It should thus provide for adhesion of the filaments on thedrum periphery; it should protect the drum surface; and it shouldimprove the working of the stripper member on the drum. Finally, itshould increase the cohesion of the fibers made from the filaments inthe fibrous structure. This was quite diflicult since the variouscomponents of the liquid had to be intermiscible and, in addition, itwas desirable that they should take effect in sequence one after theother. Sometimes it was even necessary to add dyes or other coatingmaterials.

The dosage regarding the application of specific amounts of coatingmaterials in a specific period of time of application was quitediflicult because the various components could not be applied very oftenin the sequence of time. On the one hand, only as much coating liquidshould be applied as is necessary to improve the taking of the fibers bythe drum. On the other hand, it is desirable to provide individualfibers formed on the drum after removal therefrom, with sufficientcoating material to improve their abrasion and the cohesion of thefibers in the fibrous structure. An overdose is harmful because thefilaments, on their way along the periphery of the drum during theattenuation, and in their travel up to the stripper, have a tendency tolose part of the liquid such as a lubricant and deposit the liquid onthe drum surface. The lubricant which then sticks to the drum surfacehas a tendency to soil the surface and it also decomposes because of thecontinuous friction between the stripper and the drum. As a result,residues are formed on the drum and on the stripper which interfere withthe further drawing of the fibers by the drum and the splitting of thefilaments to individual fibers. The residues which are finely dividedand mixed with minute parts of the filaments themselves form a kind ofemery paste which is harmful to the surface of the drum and makes itprogressively less suited for further formation of fibers.

The problem, thus, is either to spare the surface of the drum by too lowan amount of coating liquid and, in that case, to provide for too smalla dose of liquid for the fibers to improve their cohesion, or on theother hand, to use an overdose which will result in the necessity todiscontinue the production from time to time to clean the drum surfaceand the stripper.

Too low or too large an amount has also an undesirable effect on thespinning process itself, that is on the formation of the filaments onthe spinning cones at the heated end section of glass rods or under thespinning nipples of the trough or channel which contains the liquidglass. The attenuation and drawing on the drum is also affected thereby.Whenever the filaments received on the drum have too little coatingliquid, they will not adhere sufiiciently to the drum surface and willthen be drawn with uneven thicknesses because of the slippage. Thisagain results in deviations of the diameter of the filaments and causesthe jerky drawing of the filaments by the drum which thus may be subjectto tearing or if the taking ofr is interrupted for just a brief instant,may be subject to burning away during taking-01f.

The soiling of the drum surface and of the stripper has also a badefiect on the spinning process since the filaments will be liable tomore or less float on the drum surface which again results in an uneventhickness of the filaments or fibers.

An adequate and sufliciently distributed lubricant is mainlyindispensable in the manufacture of glass fibersli vers with respect tothe uniformity and the tensile strength of such a silver and the yarneventually twisted from the sliver. The uneven amount of lubricant inparticular results in an uneven strength which again causes uneventensioning in the further processing and thus a yarn of unevenproperties. In the conventional devices, it was usually up to the crewwhich operated the machine to provide the coating device with more orless lubricant or other coating liquid. Usually considerable andsometimes unacceptable variations occurred, such as a variation between0.2 and 0.8% of lubricant. It must be borne in mind in this connectionthat the crew of course was, in the first place, interested in providingfor smooth operation of the drum and the stripper, and in particular toavoid rvisible soiling of the drum surface. Therefore, even in thosecases where the fibrous structure would have required a higher amount oflubricant the crew usually tried to get along with a smaller amount inorder to make sure that the operation would not be interrupted. Thedefects in the fibrous structure were not as apparent immediately to thecrew as any soiling of the drum.

A solution to all these problems appeared at first in a process where alubricant which provided for only weak adhesion between the fibers wasapplied only after formation of the fibrous structure. This, however,was undesirable since in this case the fibers that were in the fibrousbody structure at a greater distance from the coating device, which forinstance might be a spraying device, would not receive a sufficientamount of lubricant, since the whole procedure was a surface applicationonly. This is particularly apparent in case of the formation of a staplefiber ribbon or sliver. It was found in practical use that it wasimpossible to penetrate into the core of the sliver with the lubricant.This again affected the tensile strength of the sliver and was quiteharmful in view of the subsequent winding operation which requiredseveral turns for the sliver and it also showed up in the subsequenttreatment to a yarn.

SUMMARY OF THE INVENTION It is therefore an object of the invention toprovide for a coating process for glass fibers wherein an adequate andevenly distributed amount of lubricant or other coating liquid is placedas well to the filaments as to fibers generating from the filaments.

Another purpose is a process of this kind wherein a soiling of the drumsurface or stripper is avoided.

Another object of the invention is a coating process and apparatus forit wherein fibers of even thickness and uniform properties can beproduced, and in particular where in case of fibrous structures thefibers in the interior of the structures have the same properties as atthe surface.

These various objects are met by an improvement in the process of makingglass fiber structures wherein liquid coated glass filaments are passedto a drawing drum where they are attenuated and separated intoindividual glass fibers which are then consolidated to glass fiberstructures, the improvement comprising the steps of applying coatedliquid in separate applications, first by coating the filaments prior totheir delivery to the drawing drum and then by coating the fibers aftertheir formation on said drum and prior to their consolidation into glassfiber structures.

The invention also embraces an apparatus for applying a liquid coatingmedium to glass fibers, the apparatus comprising a drawing drum forattenuating the glass filaments to individual glass fibers, guide wallsforming an air channel of a width extending substantially across all ofthe periphery of the said drum and of a general axial directiontangentially away from the periphery of the drum, means for generating astream of air in said channel for carrying the fibers away from saiddrum, and liquid-transfer means projecting into the said channels so asto protrude into the paths of the fibers carried by said stream of air.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 illustrates in a partialcross-section and on a reduced scale an apparatus for making a flatfiber body such as a fleece or a mat;

FIG. 2 is a partial vertical section through another embodiment of theinvention, the apparatus of this figure being useful particularly formaking a ribbon-shaped fiber structure; and

FIG. 3 a partial vertical section through another embodiment of theinvention showing this embodiment in a partial view in the same manneras in FIG. 2.

DESCRIPTION OF PREFERRED EMBODIMENTS As has been stated, the process ofthe invention is characterized by the fact that the coating of thefilaments being continuously drawn on the one hand, and of theindividual fibers generating of the filaments on the other hand, ispracticed in two separate application steps. .As will be describedfurther below, the coating may be effected, in case of the fibers, bycarrying the fibers in an air stream along guide walls and bringing theminto con tact with coating means which protrude into the air stream andapply a coating before and while the fibers are consolidated to afibrous body.

The fibers are thus coated separately from the filaments and, if wanted,different coating materials may be used, such as lubricants, adhesives,binders, dyes, etc. It is not necessary, during coating of the fibers,to take into account the requirements of the spinning process for thefilaments, but rather the second coating may be directed only to thefinal use and processing of the product formed by the fibers. It isfurthermore possible with this type of procedure to keep the surface ofthe drum clean from the lubricant for the further taking-oil of thefilaments and also to apply the coating in exactly the amounts that arenecessary.

With specific reference now to FIG. 1, it should be noted that this typeof apparatus is particularly useful for making two-dimensional glassfiber bodies, for instance by the process of German Pat. 976,682. Thedevice comprises a drawing drum 1 that rotates with high speed and ontowhich are propelled the filaments f in parallel alignment and in a verylarge number, for instance up to 500, after being coated by a coatingdevice d of conventional structure, for instance a coating ledge, to adegree adequate to secure the adhesion of the filaments to the drum withthe coating device d several rows of fibers can also become forced, asshown into one plane 1''. The filaments are then attenuated on the drumand conducted to the stripper 2. This movement is effected partly indirect contact with the surface of the drum and partly within an area ofrotation which is generated by the revolving drum and carries thefilaments within the adjacent layer of air that revolves with the drum.The stripper 2 extends tangentially or close to tangentially from theperiphery of the drum and is secured on a pivot axis 3. The drum 1 movesin a housing which partly encircles the drum and may be called the apronand which confines the area of rotation close to the drum surface. Thisapron is formed by the wall indicated as 4 in the drawing. A turn memberfor change of direction is formed by the continuation of the channelformed between the drum surface and the interior of the apron wall. Thisturn member is indicated as 5 in the drawing and connects with anadjacent guide wall 6 which will cause the fibers to move to the placewhere they are consolidated to a fibrous structure.

The filaments which move when the drum 1 revolves in the direction ofthe arrow A and which are, after completing less than one revolution,taken off from the drum, are then split up during the take-off intofibers of uneven length moving in an air stream S.

At a suitable place, there is provided a revolving coating roller 7, thedirection of revolution indicated by the arrow B. Conveniently, thisroller is provided at the turn member 5, but it could also be providedin the horizontally extending guide wall 6. The coating roller eitherdips into a receptacle for the liquid medium or as shown is suppliedcontinuously with the medium by means of a dripping or spraying device8..-

The roller 7 has an axis 9 which is supported outside of the turn member5. The roller extends through a gap in the wall of the turn member intothe interior of the air channel with a portion of its circumferenceindicated as 10. Thus, the roller interrupts the guide wall formed bythe turn member and the guide wall 6. The individual fibers musttherefore pass the surface of the coating roller and come into contacttherewith and thus will carry away the necessary amount of liquidcoating medium.

Thus, it is accomplished that the individual fibers receive a sufficientamount of coating medium between the place of their formation on thedrum and the place of their consolidation to a fibrous structure. As aresult of this kind of application procedure and apparatus, all of, orpractically all of the fibers in the final product will be coatedadequately with the liquid coating medium, and the amount of coatingwill not depend upon their relative position in the fiber structure oron the amount of coating applied to the intermediate product consistingof the glass fibers.

This is important, since it is very difiicult to apply the right amountin case of thin glass fiber structures as they are for instance embeddedin bituminous glass fiber mat roofings, continuous corrosion wrappingsfor tubes or containers, etc. The cross-section of glass fiber mats forthese products usually is only a fraction of a millimeter and, in thiscase, it is almost impossible, with the conventional devices, to obtaina uniform distribution of a liquid coating material. The problem is evenworse with conventional devices in case of the lubrication of thefilaments by means of a pad or by using a spray device for making aribbon-shaped fibrous structure. In this case, the coating liquid, forinstance an adhesive containing liquid, can usually not be caused topenetrate into the core of the glass fiber ribbon or sliver. However,with the process and apparatus of the invention it is possible to causethe liquid to coat, even in case of a ribbon-shaped structure, thefibers throughout the cross-section and in a uniform and adequatemanner. Tests have shown that this results in a substantial increase ofthe tensile strength of the sliver.

FIG. 2 shows in schematic form an embodiment wherein a cylinder 21 isprovided with a transfer elements 28 to form a strip of absorbentmaterial, for instance a felt, which extends through a gap into thecylinder 27 and is supplied from the exterior with liquid. The felt 28extends to an extent into the interior 29 of the cylinder that thefibers, which move into the cylinder along the curved guide wall 30 andform a vortex w along the inner surface of the cylinder, will contactthe inner edge 31 of the felt 28 and absorb liquid therefrom. The felt28 can be supported in a housing 32 and may receive its liquid from areceiver 33 provided at the outer end of the housing. The amount ofwetting of the fibers will depend on the absorptive properties of thefelt, on the level of treating liquid in the receptacle 3'3 and on thelength of protrusion of the portion 31 of the felt.

It will be understood that it is also possible to use several of thedifferent types of transfer members in combination. Besides, there areother means of increasing the intensity of the wetting action. It is forinstance possible to remove the felt 28 if a particularly high amount ofcoating liquid, for instance an amount above 1%, is required. A lip 34may then be used which extends in the form of a groove or channel acrossthe entire width of the cylinder 27 and replaces the stripper edge 31 ofthe felt. In this groove, a constant amount of liquid will be maintainedby flowing from the receptacle 33 through the housing 32 that in thiscase forms a liquid supply channel and is not occupied by the felt. Thewhirling individual fibers will contact the lip formed at the one sideof the groove 34 and will thus directly obtain a liquid coating.

FIG. 3 illustrates still another embodiment which may be used inproducing staple fiber slivers and which is of a particularly simpledesign requiring very little service. This embodiment in additionpermits an uninterrupted and particularly well adjustable wetting of thefibers. The cylinder 27 in this case is provided with a slit-shapedopening 35 that extends through its entire width or through the majorparts of its width. The liquid transfer medium itself is disposed orsuspended in this slit and thus protrudes into the cylinder 27. Themember in the form of a shelf is indicated by the reference numeral 36.A particcularly useful form of transfer medium is a wire mesh of narrowopenings which may for instance be fastened to a support tongue or shaft37. The interior end of the support member and wire mesh may be slightlybent inwards in order to present an obstacle to the fiber stream and tomake sure that the fibers will contact the wire mesh. This type of afine mesh wire sieve has the advantage of little service and longer lifeas against a felt which will be subject to wear after an extended timeof operation and which also may be liable to rigidify and harden becauseof the clogging up with particles of the liquid medium which do notevaporate. Thus, this kind of embodiment is a further means to avoidvariation of the coating liquid in the fiber product, such as a sliverof glass fibers, which may still occur with the use of a felt.

The wire mesh which is secured to a support tongue is of almostunlimited durability and can easily be cleaned by washing in case ofsoiling. By means of a dosing device (not shown) the liquid is suppliedto the transfer element through a dropping device 38. The coating liquidmay for instance comprise an adhesive or a dye. The wire mesh in thiscase has the function to distribute uniformly the applied coating liquidand to keep it available while, with the use of a smooth surface, thecoating liquid may be subject to uncontrolled draining or dripping. Ahinge 39 permits to snap open the portion 40 of the cylinder forcleaning or similar purposes.

We claim:

1. In a process of making glass fiber structures, the steps of passingglass filaments over a drawing drum to attenuate the filaments; liftingthe attenuated filaments from said drum and separating the same intoindividual fibers; transporting said individual fibers separated fromeach other in an air stream away from said drum; applying a coatingliquid to said filaments prior to their delivery to said drawing drum;and applying a further coating liquid to said individual fibers whilethey are transported by said air stream and prior to their consolidationinto a glass fiber structure.

2. The process of claim 1, wherein the glass fiber structure is a glassfiber mat, fleece, sliver, or threedimensional body.

3. The process of claim 1, wherein at least one of the coating liquidsis a lubricating liquid.

4. The process of claim 1, wherein the fibers after leaving said drumare carried in a continuous air current Within definite boundaries on apath leading to the place of consolidation to a fibrous structure andwherein the said application of said further coating liquid is effectedby bringing the individual fibers in physical contact with liquidtransfer members, while the fibers move within said boundaries alongsaid path.

5. In an apparatus for making glass fiber structures, a combinationcomprising a rotating drawing drum for attenuating glass filaments toindividual fibers; means for applying a coating liquid to the filamentsupstream of said drawing drum; guide wall means forming an air channelof a width substantially equal to the length of said drum and leading insubstantially tangential direction away from the periphery of said drum;means for generating a stream of air in said channel for carrying thefibers separated from each other away from said drum; and coating liquidtransfer means projecting into said channel so as to protrude into thepath of the fibers carried by said air stream to apply a coating liquidto the individual fibers while they are transported by said air stream.

6. The combination as defined in claim 5, wherein said transfer meansrevolves in a plane substantially parallel to the direction of saidchannel.

7. The combination as defined in claim 6, and including means to applyfluid to the periphery of said revolving transfer means.

8. The combination as defined in claim 5, which includes a strippermember extending substantially across the entire periphery of said drumand being directed tangentially way from said drum for removing saidfibers from said drum, the stripper member forming part of saidchannel-forming guide walls.

9. The combination as defined in claim 5, wherein said channel-formingguide walls comprise a cylinder and wherein a gap is provided in theperipheral Wall of said cylinder, said transfer means protruding throughsaid gap into the interior of said cylinder.

10. The combination as defined in 9, wherein the transfer means is inthe form of at least one stationary member.

11. The combination as defined in claim 9, wherein the transfer memberis in the form of a strip of absorptive material extending with one edgeinto the cylinder through the periphery thereof.

12. The combination as defined in claim 11, and including a hollowholding member for said strip disposed substantially outside saidcylinder and having one end extending through said gap in said cylinderinto the interior thereof, and a receptacle for the liquid, saidreceptacle being disposed at the other end of said holding member and incommunication with the opposite end of said strip of absorptivematerial.

13. The combination as defined in claim 9, and including a liquidholding receptacle, a duct leading from said receptacle through said gapin said cylinder into the interior thereof, and means defining a grooveformed at the inner end of said duct and extending in axial direction ofsaid cylinder, the level of liquid in said groove being therebydependent on the level of liquid in said receptacle.

14. The combination as defined in claim 9, and including a shelfextending from said gap into the interior of said cylinder, said shelfbeing adapted to hold and dispense liquid to the fibers when contactedby the same, and means for applying said liquid to said shelf throughsaid gap.

15. The combination as defined in claim 14, wherein said shelf is in theform of a wire mesh.

16. The combination as defined in claim 14, wherein said shelf is in theform of a support member and including a wire mesh secured to the topside of said support member.

References Cited UNITED STATES PATENTS 2,198,519 4/1940 Tarr 1182442,566,643 9/1951 Tooley l1 2,961,821 11/1960 Marzocchi 57-35 2,996,1028/1961 Schuller 65-11 3,080,736 3/1963 Mabru 65-1 3,220,811 11/1965Schuller 65-9 3,492,103 l/ 1970 Schuller 65l1 3,498,263 3/1970 De Toledo118234 S. LEON BASHORE, Primary Examiner R. H. ANDERSON, AssistantExaminer US. Cl. X.R.

65-4, 11 R; ll8223, 245, 255

